When Swedish software engineer Johan Kanflo needed a very slim radio node for a project, he found himself in a predicament.
Kanflo had been using Tiny328, a mini wireless Arduino clone developed by another DIY specialist named Nathan Chantrell, but needed something even smaller.
The AAduino, as he calls it, is a wireless Arduino clone the size of a AA battery. He made the device to include Keystone battery terminals rotated 180° to act as positive and negative terminals. The AAduino is powered by an ATMega328p and fitted with an RFM69C companion. There’s even room for two DS18B20 temperature sensors and an indicator LED.
Kanflo designed the AAduino to run at 8Mhz to allow for a longer life span and was fashioned to fit inside of a 3-AA battery holder in order to create a very small wireless node.
If you want to make one yourself, Kanflo includes schematics, bill of material and a sample program to test the hardware on Github.